diff options
| -rw-r--r-- | library/alloc/src/rc.rs | 59 | ||||
| -rw-r--r-- | library/alloc/src/sync.rs | 60 | ||||
| -rw-r--r-- | library/alloc/tests/arc.rs | 15 | ||||
| -rw-r--r-- | library/alloc/tests/rc.rs | 15 |
4 files changed, 12 insertions, 137 deletions
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs index f3cbfe27b3e..5f307069d80 100644 --- a/library/alloc/src/rc.rs +++ b/library/alloc/src/rc.rs @@ -1441,48 +1441,6 @@ impl<T> Rc<[T]> { } } - /// Create an `Rc<[T]>` by reusing the underlying memory - /// of a `Vec<T>`. This will return the vector if the existing allocation - /// is not large enough. - #[cfg(not(no_global_oom_handling))] - fn try_from_vec_in_place(mut v: Vec<T>) -> Result<Rc<[T]>, Vec<T>> { - let layout_elements = Layout::array::<T>(v.len()).unwrap(); - let layout_allocation = Layout::array::<T>(v.capacity()).unwrap(); - let layout_rcbox = rcbox_layout_for_value_layout(layout_elements); - let mut ptr = NonNull::new(v.as_mut_ptr()).expect("`Vec<T>` stores `NonNull<T>`"); - if layout_rcbox.size() > layout_allocation.size() - || layout_rcbox.align() > layout_allocation.align() - { - // Can't fit - calling `grow` would involve `realloc` - // (which copies the elements), followed by copying again. - return Err(v); - } - if layout_rcbox.size() < layout_allocation.size() - || layout_rcbox.align() < layout_allocation.align() - { - // We need to shrink the allocation so that it fits - // https://doc.rust-lang.org/nightly/std/alloc/trait.Allocator.html#memory-fitting - // SAFETY: - // - Vec allocates by requesting `Layout::array::<T>(capacity)`, so this capacity matches - // - `layout_rcbox` is smaller - // If this fails, the ownership has not been transferred - if let Ok(p) = unsafe { Global.shrink(ptr.cast(), layout_allocation, layout_rcbox) } { - ptr = p.cast(); - } else { - return Err(v); - } - } - // Make sure the vec's memory isn't deallocated now - let v = mem::ManuallyDrop::new(v); - let ptr: *mut RcBox<[T]> = ptr::slice_from_raw_parts_mut(ptr.as_ptr(), v.len()) as _; - unsafe { - ptr::copy(ptr.cast::<T>(), &mut (*ptr).value as *mut [T] as *mut T, v.len()); - ptr::write(&mut (*ptr).strong, Cell::new(1)); - ptr::write(&mut (*ptr).weak, Cell::new(1)); - Ok(Self::from_ptr(ptr)) - } - } - /// Constructs an `Rc<[T]>` from an iterator known to be of a certain size. /// /// Behavior is undefined should the size be wrong. @@ -2008,17 +1966,12 @@ impl<T> From<Vec<T>> for Rc<[T]> { /// assert_eq!(vec![1, 2, 3], *shared); /// ``` #[inline] - fn from(v: Vec<T>) -> Rc<[T]> { - match Rc::try_from_vec_in_place(v) { - Ok(rc) => rc, - Err(mut v) => { - unsafe { - let rc = Rc::copy_from_slice(&v); - // Allow the Vec to free its memory, but not destroy its contents - v.set_len(0); - rc - } - } + fn from(mut v: Vec<T>) -> Rc<[T]> { + unsafe { + let rc = Rc::copy_from_slice(&v); + // Allow the Vec to free its memory, but not destroy its contents + v.set_len(0); + rc } } } diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs index 37e07eb5998..b69f6b03112 100644 --- a/library/alloc/src/sync.rs +++ b/library/alloc/src/sync.rs @@ -1261,49 +1261,6 @@ impl<T> Arc<[T]> { } } - /// Create an `Arc<[T]>` by reusing the underlying memory - /// of a `Vec<T>`. This will return the vector if the existing allocation - /// is not large enough. - #[cfg(not(no_global_oom_handling))] - fn try_from_vec_in_place(mut v: Vec<T>) -> Result<Arc<[T]>, Vec<T>> { - let layout_elements = Layout::array::<T>(v.len()).unwrap(); - let layout_allocation = Layout::array::<T>(v.capacity()).unwrap(); - let layout_arcinner = arcinner_layout_for_value_layout(layout_elements); - let mut ptr = NonNull::new(v.as_mut_ptr()).expect("`Vec<T>` stores `NonNull<T>`"); - if layout_arcinner.size() > layout_allocation.size() - || layout_arcinner.align() > layout_allocation.align() - { - // Can't fit - calling `grow` would involve `realloc` - // (which copies the elements), followed by copying again. - return Err(v); - } - if layout_arcinner.size() < layout_allocation.size() - || layout_arcinner.align() < layout_allocation.align() - { - // We need to shrink the allocation so that it fits - // https://doc.rust-lang.org/nightly/std/alloc/trait.Allocator.html#memory-fitting - // SAFETY: - // - Vec allocates by requesting `Layout::array::<T>(capacity)`, so this capacity matches - // - `layout_arcinner` is smaller - // If this fails, the ownership has not been transferred - if let Ok(p) = unsafe { Global.shrink(ptr.cast(), layout_allocation, layout_arcinner) } - { - ptr = p.cast(); - } else { - return Err(v); - } - } - // Make sure the vec's memory isn't deallocated now - let v = mem::ManuallyDrop::new(v); - let ptr: *mut ArcInner<[T]> = ptr::slice_from_raw_parts_mut(ptr.as_ptr(), v.len()) as _; - unsafe { - ptr::copy(ptr.cast::<T>(), &mut (*ptr).data as *mut [T] as *mut T, v.len()); - ptr::write(&mut (*ptr).strong, atomic::AtomicUsize::new(1)); - ptr::write(&mut (*ptr).weak, atomic::AtomicUsize::new(1)); - Ok(Self::from_ptr(ptr)) - } - } - /// Constructs an `Arc<[T]>` from an iterator known to be of a certain size. /// /// Behavior is undefined should the size be wrong. @@ -2615,17 +2572,12 @@ impl<T> From<Vec<T>> for Arc<[T]> { /// assert_eq!(&[1, 2, 3], &shared[..]); /// ``` #[inline] - fn from(v: Vec<T>) -> Arc<[T]> { - match Arc::try_from_vec_in_place(v) { - Ok(rc) => rc, - Err(mut v) => { - unsafe { - let rc = Arc::copy_from_slice(&v); - // Allow the Vec to free its memory, but not destroy its contents - v.set_len(0); - rc - } - } + fn from(mut v: Vec<T>) -> Arc<[T]> { + unsafe { + let rc = Arc::copy_from_slice(&v); + // Allow the Vec to free its memory, but not destroy its contents + v.set_len(0); + rc } } } diff --git a/library/alloc/tests/arc.rs b/library/alloc/tests/arc.rs index eb379e4d6a1..ce40b5c9b0a 100644 --- a/library/alloc/tests/arc.rs +++ b/library/alloc/tests/arc.rs @@ -210,18 +210,3 @@ fn weak_may_dangle() { // `val` dropped here while still borrowed // borrow might be used here, when `val` is dropped and runs the `Drop` code for type `std::sync::Weak` } - -#[test] -fn arc_from_vec_opt() { - let mut v = Vec::with_capacity(64); - v.push(0usize); - let addr = v.as_ptr().cast::<u8>(); - let arc: Arc<[_]> = v.into(); - unsafe { - assert_eq!( - arc.as_ptr().cast::<u8>().offset_from(addr), - (std::mem::size_of::<usize>() * 2) as isize, - "Vector allocation not reused" - ); - } -} diff --git a/library/alloc/tests/rc.rs b/library/alloc/tests/rc.rs index 1d5f3c52006..efb39a60966 100644 --- a/library/alloc/tests/rc.rs +++ b/library/alloc/tests/rc.rs @@ -206,18 +206,3 @@ fn weak_may_dangle() { // `val` dropped here while still borrowed // borrow might be used here, when `val` is dropped and runs the `Drop` code for type `std::rc::Weak` } - -#[test] -fn rc_from_vec_opt() { - let mut v = Vec::with_capacity(64); - v.push(0usize); - let addr = v.as_ptr().cast::<u8>(); - let rc: Rc<[_]> = v.into(); - unsafe { - assert_eq!( - rc.as_ptr().cast::<u8>().offset_from(addr), - (std::mem::size_of::<usize>() * 2) as isize, - "Vector allocation not reused" - ); - } -} |